Technical Field
The present invention relates generally to a device and methods to convert wavelengths and, in particular, to signal wavelength conversion while maintaining polarization information.
Description of the Related Art
Due to the ever increasing demand from applications such as video sharing and streaming, machine-to-machine communications, mobile data and gaming, as well as emerging internet-based applications, core network traffic continues to grow at a double digit rate. In order to handle this continuous growth in traffic demand, carrier networks increase their capacity in a scalable and cost-effective manner. It is therefore paramount for network operators to become more efficient in data transport.
Existing approaches address the problem of continuous growth of in traffic demand for carrier networks using all-optical wavelength conversion (AOWC) are complex and cost-ineffective. Additionally, polarization insensitivity creates signal power fluctuation in, e.g., traditional 10 G/40 G networks and also cause polarization dependent loss (PDL), thus, e.g., causing a performance drop for the current 100 G, future 400 G/IT networks, and beyond, where polarization-multiplexed transmission is used for improved spectral efficiency. With the current state of AOWC, the conversion range is a concern. Achieving full range conversion in C-band, L-band, or both is needed, especially since it is quite difficult to achieve AOWC with wide bandwidth in practice without using complicated dispersion management in fiber.
To achieve enough signal conversion gain using AOWC, either a large nonlinearity coefficient or huge optical pump power may be needed, which can result in having to invest in either new nonlinearity fiber, which is scarce in supply, or high power optical amplifiers, which are expensive and costly to operate. Furthermore, in order to achieve the desired WC gain, some demonstrations have to avoid stimulated Brillouin scattering (SBS) in nonlinear fiber by applying certain engineering techniques, such as phase modulating the pump lasers or stretching the fiber sections at different tensions, which create additional cost and complexity.